Modular aftertreatment assembly

ABSTRACT

A modular aftertreatment assembly for an engine system is provided. The modular aftertreatment assembly includes a housing having a first section, a second section, and a third section. The modular aftertreatment assembly also includes a mixing tube positioned within and extending from the second section of the housing. The modular aftertreatment assembly further includes a diffusion assembly having a first diffusion and a second diffusion plate. The modular aftertreatment assembly includes a selective catalytic reduction assembly. The modular aftertreatment assembly also includes a plurality of perforations provided on an outlet face of the first bank of the plurality of catalysts and the second bank of the plurality of catalysts respectively. The modular aftertreatment assembly further includes a pair of outlets provided in association with the first and third sections of the housing respectively.

TECHNICAL FIELD

The present disclosure relates to an aftertreatment assembly, and more particularly to a modular aftertreatment assembly for an engine system.

BACKGROUND

An aftertreatment assembly is associated with an engine system. The aftertreatment assembly is configured to treat and reduce oxides of nitrogen (NOx) present in an exhaust gas flow, prior to the exhaust gas flow exiting into the atmosphere. In order to reduce NOx, the aftertreatment system may include a reductant injector, a mixing tube, and a Selective Catalytic Reduction (SCR) module. The reductant injector is configured to inject a reductant into the exhaust gases, before the exhaust gases flow through the SCR module.

In some applications, the components of the aftertreatment assembly, such as the SCR module and the mixing tube, occupy a large amount of space in an engine enclosure. Accordingly, in case of small size applications having spatial constraints, it may be difficult to accommodate such large sized aftertreatment components within a confined space. However, re-sizing the aftertreatment components to accommodate the aftertreament assembly in the confined space may affect an overall working and efficiency of the aftertreatment assembly. For example, in some situations, smaller sized aftertreatment components have other operational issues, such as an increase in back pressure experienced by the components of aftertreatment assembly.

U.S. Pat. No. 8,752,370, hereinafter referred to as '370 patent, describes an exhaust aftertreatment system including housing with two or more inlets configured to receive separate entering exhaust streams from an engine. The system includes two or more first exhaust treatment devices, each configured to receive one of the separate entering exhaust streams in a first direction. The system further includes two or more redirecting flow passages configured to combine the separate exhaust streams into a merged exhaust stream that flows in a second direction about 180 degrees from the first direction and an intermediate flow region configured to divide the merged exhaust stream into two or more separate exiting exhaust streams. The system also includes two or more second exhaust treatment devices, each configured to receive one of the separate exiting exhaust streams in a third direction about 90 degrees from the second direction.

In the '370 patent, the components of the exhaust aftertreatment system include two separate inlets for receiving separate exhaust streams from the engine. Further, the design of the exhaust aftertreatment system of the '370 patent is not compact, and the components of the exhaust aftertreatment system do not fit in a small space.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a modular aftertreatment assembly for an engine system is provided. The modular aftertreatment assembly includes a housing having a first section, a second section, and a third section. The first section, the second section, and the third section are positioned adjacent to each other in a parallel arrangement, such that the second section is centrally disposed within the housing. The modular aftertreatment assembly also includes a mixing tube positioned within and extending from the second section of the housing. The mixing tube includes an inlet end and an outlet end. The inlet end of the mixing tube is configured to couple to an exhaust conduit of the engine system. Further, the outlet end of the mixing tube includes a plurality of slots on a top facing surface and a bottom facing surface of the mixing tube. The modular aftertreatment assembly further includes a diffusion assembly having a first diffusion plate positioned between the first and second sections of the housing, and a second diffusion plate positioned between the second and third sections of the housing. The first and second diffusion plates include a plurality of openings respectively. The diffusion assembly is positioned parallel to the mixing tube. The modular aftertreatment assembly includes a selective catalytic reduction assembly having a first bank of a plurality of catalysts and a second bank of a plurality of catalysts. The first bank of the plurality of catalysts is positioned within the first section of the housing and the second bank of the plurality of catalysts is positioned within the third section of the housing. The modular aftertreatment assembly also includes a plurality of perforations provided on an outlet face of the first bank of the plurality of catalysts and the second bank of the plurality of catalysts respectively. The modular aftertreatment assembly further includes a pair of outlets provided in association with the first and third sections of the housing respectively.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary engine system and a modular aftertreatment assembly provided in association with the engine system, according to one embodiment of the present disclosure;

FIG. 2 is a perspective view of the modular aftertreatment assembly, according to one embodiment of the present disclosure; and

FIG. 3 is a perspective view of a mixing tube and a diffusion assembly associated with the modular aftertreatment assembly of FIG. 2, according to one embodiment of the present disclosure; and

FIG. 4 is a perspective view of a portion of a selective catalytic reduction assembly associated with the modular aftertreatment assembly of FIG. 2, according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. FIG. 1 is a perspective view of an exemplary engine system 100, according to one embodiment of the present disclosure. In one embodiment, the engine system 100 may be associated with a locomotive (not shown). However, it should be noted that the application of the present disclosure is not restricted to the locomotive. The engine system 100 may be used to provide power to any machine including, but not limited to, an on-highway truck, an off-highway truck, an earth moving machine, and other similar machines.

As shown in the accompanying figures, the engine system 100 is mounted on a frame 102 of the locomotive. The engine system 100 includes an engine 104. The engine 104 provides driving power to the locomotive, in order to propel the locomotive on rails (not shown). In one embodiment, the engine 104 may include, for example, a diesel engine, a gasoline engine, a gaseous fuel powered engine such as, a natural gas engine, a combination of known sources of power, or any other type of power source apparent to one of skill in the art. The engine 104 may include an intake manifold (not shown) and an exhaust manifold (not shown). The intake manifold is configured to receive intake air through an air intake system. Products of combustion may be exhausted from the engine 104 via the exhaust manifold of the engine 104. Additionally, the locomotive may include other components, such as, a fuel system (not shown) and an aftercooler 106 associated with the engine 104 and a torque converter 108.

The engine system 100 includes a modular aftertreatment assembly 200. The modular aftertreatment assembly 200 is configured to treat the exhaust gases exiting the exhaust manifold of the engine 104. The modular aftertreatment assembly 200 is provided in fluid communication with the exhaust manifold of the engine 104 via an exhaust conduit (not shown).

Referring to FIG. 2, the modular aftertreatment assembly 200 includes a housing 202. The housing 202 is embodied as a generally rectangular cuboid.ca The housing 202 may be made of a metal, based on system requirements. Dimensions of the housing 202 may vary based on an amount of the exhaust gases that may be received by the modular aftertreatment assembly 200. The housing 202 includes bracket elements 204 for receiving mechanical fasteners in order to mount the modular aftertreatment assembly 200 on a work surface. The bracket elements 204 may include isolation components to isolate transfer of any vibrations to and from the modular aftertreatment assembly 200. The housing 202 includes a first section 206, a second section 208, and a third section 210. The first, second, and third sections 206, 208, 210 are positioned adjacent to each other in a parallel arrangement. The second section 208 is centrally disposed between the first and third sections 206, 210 of the housing 202.

Each of the first, second, and third sections 206, 208, 210 are embodied as separate components and are assembled together to form the housing 202. Each of the first, second, and third sections 206, 208, 210 include flanges 212, 214, 216 (see FIGS. 3 and 4) respectively for receiving mechanical fasteners in order to couple the first section 206 with the second section 208 and the second section 208 with the third section 210 respectively. Alternatively, the housing 202 may embody a unitary component with the first, second, and third sections 206, 208, 210 defined therein. For illustrative and explanation purposes, some portions of the first, second, and third sections 206, 208, 210 are shown transparent in the accompanying figures, in order to depict mounting positions and details of the components of the modular aftertreatment assembly 200 present therein.

A reductant injector 236 is positioned along a mixing tube 218, close to an inlet end 220 thereof. A reductant is injected into the mixing tube 218 by the reductant injector 236. The reductant may be a fluid, such as, Diesel Exhaust Fluid (DEF). The reductant may include urea, ammonia, or other reducing agent known in the art. The reductant may be received from a reductant tank (not shown) associated with the engine system 100.

Referring to FIGS. 2 and 3, the second section 208 of the housing 202 defines an interior space therewithin. The interior space is configured to receive the mixing tube 218. A portion of the mixing tube 218 extends outwards from the second section 208 of the housing 202. The mixing tube 218 includes the inlet end 220 and an outlet end 222, such that the inlet end 220 is positioned externally with respect to the second section 208 of the housing 202. The inlet end 220 of the mixing tube 218 is coupled to the exhaust conduit of the engine 104, and is configured to receive a main stream 228 of the exhaust gases therefrom. The modular aftertreatment assembly 200 of the present disclosure has a single inlet to receive the exhaust gases into the modular aftertreatment assembly 200. A direction of flow of the exhaust gases into and within the modular aftertreatment assembly 200 is shown using arrows “F” in FIG. 2. The inlet end 220 includes a circular flange portion 224 to couple the mixing tube 218 to the exhaust conduit.

Additionally or optionally, in order to promote mixing of the reductant with the main stream 228 of the exhaust gases, a mixing element 238 is associated with the modular aftertreatment assembly 200. The mixing element 238 is provided within the mixing tube 218. The mixing element 238 is positioned downstream of the reductant injector 236, with respect to the flow direction “F” of the exhaust gases. In one embodiment, the mixing element 238 may include a flapper style mixer. Alternatively, the mixing element 238 may include a swirl plate mixer. Although a single mixing element 238 is illustrated herein, the modular aftertreatment assembly 200 may include two or more mixing elements, such that a type of each of the mixing elements may be same or different, based on system requirements.

The mixing tube 218 includes the outlet end 222. As shown in the accompanying figures, the outlet end 222 includes a number of slots 226. The slots 226 extend in a direction parallel to the flow “F” of the exhaust gases. The slots 226 have an oblong shape and are provided on a top facing surface 234 and a bottom facing surface (not shown) of the mixing tube 218. The main stream 228 of the exhaust gases enters the modular aftertreatment assembly 200 from the inlet end 220, flows towards the outlet end 222, and further divides into a first exhaust gas flow 230 and a second exhaust gas flow 232 (see FIG. 2) on impacting an end surface of the second section 208.

The first and second exhaust gas flows 230, 232 are re-routed or directed towards the first and the third sections 206, 210 respectively, through the slots 226. The slots 226 provide fluid communication between the mixing tube 218 and each of the first, second, and third sections 206, 208, 210 of the housing 202. In one example, a length of the slots 226 is approximately ¼^(th) of a length of the housing 202. The mixing tube 218 is formed by a single tube having the slots 226 provided thereon. Alternatively, the mixing tube 218 may include a two piece design such that one of the tubes includes the slots 226 provided thereon.

Referring to FIG. 3, the modular aftertreatment assembly 200 includes a diffusion assembly 240. The diffusion assembly 240 is positioned parallel to the mixing tube 218. The diffusion assembly 240 includes a first diffusion plate 242 and a second diffusion plate 244. The first diffusion plate 242 is positioned between the first section 206 and the second section 208. Further, the second diffusion plate 244 is positioned between the second section 208 and the third section 210. The first and second diffusion plates 242, 244 may perform a flow distribution function to guide and evenly distribute the exhaust gas flow 230, 232 (see FIG. 2) across a face of the respective diffusion plates 242, 244.

Each of the diffusion plates 242, 244 respectively include a number of openings 246, 248 provided across the face of the diffusion plates 242, 244. Further, each of the diffusion plates 242, 244 includes eight sections such that a sizing of the openings 246, 248 of each of the eight sections are different in order to individually tune the exhaust gas flow 230, 232 across the face of the respective diffusion plates 242, 244. More particularly, the number of openings 246, 248 is provided such that the sizing of the openings 246, 248 decreases in diameter along the direction “F” of the main stream 228 of the exhaust gases (see FIG. 2). The openings 246, 248 that are smaller in diameter are provided close to the outlet end 222 of the mixing tube 218. Such small diameter openings 246, 248 act as a restriction to the exhaust gas flow 230, 232 passing therethrough, and further direct the respective exhaust gas flows 230, 232 towards the openings 246, 248 having a comparatively larger diameter. The openings 246, 248 that are larger in diameter size are provided close to the inlet end 220 of the mixing tube 218, with respect to the direction “F” of the main stream 228 of the exhaust gases.

As shown in FIGS. 2 and 4, the modular aftertreatment assembly 200 includes a selective catalytic reduction (SCR) assembly 250. The SCR assembly 250 operates to treat exhaust gases exiting the engine 104 in the presence of ammonia, which is provided after degradation of the reductant injected into the main stream 228 of the exhaust gases near the inlet end 220. The SCR assembly 250 includes a first bank of catalysts 252. The first bank of catalysts 252 includes a number of catalysts 254 (see FIG. 4). The first bank of catalysts 252 is positioned within the first section 206 of the housing 202. The SCR assembly 250 also includes a second bank of catalysts 256 having a number of catalysts 258. The second bank of catalysts 256 is positioned within the third section 210 of the housing 202.

For illustrative purposes, the first bank of catalyst 252 associated with the first section 206 will now be explained in detail. However, it should be noted that the description of the first bank of catalyst 252 given below is equally applicable to the second bank of catalyst 256 associated with the third section 210, without limiting the scope of the present disclosure. Referring to FIGS. 2 and 4, the first bank of catalysts 252 is in fluid communication with the mixing tube 218 via the first diffusion plate 242 and the slots 226. The first diffusion plate 242 is arranged such that the first diffusion plate 242 distributes the first exhaust gas flow 230 (see FIG. 2) uniformly across inner faces (not shown) of the catalysts 254.

As shown in FIG. 4, the catalysts 254 are provided within a first frame element 264. The first frame element 264 together with the catalysts 254 are mounted within the first section 206 of the housing 202. In one example, the first bank of catalysts 252 includes eight numbers of the catalysts 254. Alternatively, the number and a length of the catalysts 254 provided per bank may vary based on system requirements. The catalysts 254 may include a circular, oval, elliptical, oblong, or any other cross section, without limiting the scope of the present disclosure. The first bank of catalysts 252 may be removably mounted within the first section 206. Further, the first bank of catalysts 252 may also be removed for cleaning or replaced as per requirements.

Further, the first frame element 264 associated with the first bank of catalysts 252 includes a number of perforations, namely a first set of perforations 266 and a second set of perforations 268. The perforations 266, 268 are provided along an outlet face 270 of the catalysts 258. The perforations 266, 268 may perform a sound attenuation function and may also reduce back pressure in the first section 206 of the housing 202. The first and second set of perforations 266, 268 extend in a direction parallel to that of the catalysts 254. In one example, the perforations 266, 268 are embodied as through holes, such that the perforations 266, 268 travel along a width of the first frame element 264. The first set of perforations 266 has a circular shape, and is centrally disposed on the first frame element 264. Whereas, the second set of perforations 268 have an approximately semi-circular shape, and are provided along a periphery of the first frame element 264. Further, the perforations 266, 268 may have a different shape than that illustrated in the accompanying figures, based on system requirements.

It should be noted that the arrangement of the SCR assembly 250 disclosed herein is exemplary in nature. The arrangement of the first and second bank of catalysts 252, 256 of the SCR assembly 250 and also the length of each of the catalysts may 254, 258 vary based on the design of the mixing tube 218 and also the rate of flow of the exhaust gases.

Referring to FIG. 2, the modular aftertreatment assembly 200 includes a pair of outlets 272, 274. The outlets 272, 274 are in fluid communication with the first and third sections 206, 210 respectively. After flowing through the first and second bank of catalysts 252, 256, the exhaust gases are let out into atmosphere through the outlets 272, 274. The outlets 272, 274 are provided on respective top surfaces 276, 278 of the first and third sections 206, 210 of the housing 202 respectively. More particularly, the outlets 272, 274 are centrally positioned on the top surface 276, 278 of the first and third sections 206, 210. Alternatively, the positions of the outlets 272, 274 may vary based on system requirements. The outlets 272, 274 may be embodied as square apertures or circular apertures. The outlets 272, 274 may be coupled to a common plenum (not shown) that receives the exhaust gases exiting the outlets 272, 274. The plenum may in turn be coupled to a stack arrangement to release the exhaust gases in to the atmosphere.

INDUSTRIAL APPLICABILITY

The modular aftertreatment assembly 200 includes a split flow design. The modular aftertreatment assembly 200 has a compact design and may be mounted in a small space. Further, the modular aftertreatment assembly 200 experiences reduced amount of backpressures owing to its design. The modular aftertreatment assembly 200 includes a single central inlet end 220 that receives and introduces the exhaust gases into the mixing tube 218. The mixing tube 218 includes the slots 226 provided at the outlet end 222. The slots 226 allow the main stream 228 of the exhaust gases to exit the mixing tube 218 without biasing the first and second bank of catalysts 252, 256. The slots 226 in the mixing tube 218 reduce space claim requirements due to increased mixing at the outlet end 222 of the mixing tube 218. The diffusion assembly 240 allows individual tuning of the respective first and second exhaust gas flows 230, 232 towards each catalyst 254, 258 of the first and second bank of catalysts 252, 256

Further, the modular aftertreatment assembly 200 disclosed herein includes a total of sixteen catalysts 254, 258. More particularly, instead of providing a single bank of catalyst, the split flow design includes two banks of catalysts 252, 256 that each includes equal number of catalysts 254, 258. The provision of two banks of catalysts 252, 256 leads to the doubling of the catalyst faces, which in turn reduces the amount of back pressure experienced by the modular aftertreatment assembly 200. Further, the perforations 266, 268 provided with respect to the bank of catalysts 252, 256 perform the sound attenuation function, and also reduce the back pressure experienced by the SCR assembly 250. The perforations 266, 268 also reduce the space claim and allow the design of the modular aftertreatment assembly 200 to be more compact.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof. 

What is claimed is:
 1. A modular aftertreatment assembly for an engine system, the modular aftertreatment assembly comprising: a housing having a first section, a second section, and a third section, wherein the first section, the second section, and the third section are positioned adjacent to each other in a parallel arrangement, such that the second section is centrally disposed within the housing; a mixing tube positioned within and extending from the second section of the housing, the mixing tube having an inlet end and an outlet end, the inlet end of the mixing tube configured to couple to an exhaust conduit of the engine system, and wherein the outlet end of the mixing tube includes a plurality of slots on a top facing surface and a bottom facing surface of the mixing tube; a diffusion assembly including a first diffusion plate positioned between the first and second sections of the housing, and a second diffusion plate positioned between the second and third sections of the housing, the first and second diffusion plates including a plurality of openings respectively, wherein the diffusion assembly is positioned parallel to the mixing tube; a selective catalytic reduction assembly including a first bank of a plurality of catalysts and a second bank of a plurality of catalysts, wherein the first bank of the plurality of catalysts is positioned within the first section of the housing, and wherein the second bank of the plurality of catalysts is positioned within the third section of the housing; a plurality of perforations provided on an outlet face of the first bank of the plurality of catalysts and the second bank of the plurality of catalysts respectively; and a pair of outlets provided in association with the first and third sections of the housing respectively. 